1. Field of the Invention
The present invention relates to Cd1-xZnxTe samples/wafers and, more particularly, to a method of annealing Cd1-xZnxTe samples/wafers.
2. Description of Related Art
Semi-insulating Cd1-xZnxTe crystals with a Zn composition typically in the 0≦x≦0.25 mole fraction range are typically used for room-temperature semiconductor x-ray and gamma-ray radiation detector applications. The semi-insulating or high electrical resistivity (≧109 Ωm) state of such Cd1-xZnxTe crystals is typically achieved by a deep-level defect compensation technique. While achieving the highly resistive state is straightforward with this technique, it is not trivial and very challenging to keep the concentration of the electrically active compensating deep-level defects sufficiently low to achieve good carrier lifetimes and mobilities.
The product of electron (e) and hole (h) mobilities (μ) and lifetimes (τ) (μeτe and μhτh respectively) are key material parameters controlling the performance of x-ray and gamma-ray detectors fabricated from semi-insulating Cd1-xZnxTe crystals. In order to achieve the necessary high electron and hole mobility lifetime products, Cd1-xZnxTe ingots and crystals are typically subjected to annealing (heat treatment) in-situ in the growth ampoule (essentially during the cool down of the as-grown ingot) or ex-situ in a post-growth annealing process, typically after the crystals are separated by slicing and dicing. The annealing process either relaxes the defect structure of the crystals or ingots (essentially reduces the concentration of harmful defects) or passivates the electrically active defects (no change in the defect concentration but reduction of the active fraction of the defects).
Notwithstanding the success of current methods of annealing semi-insulating Cd1-xZnxTe crystals, it would be beneficial for room-temperature semiconductor x-ray and gamma-ray radiation detector applications to provide semi-insulating Cd1-xZnxTe crystals that have even better electron and hole mobility lifetime product.